Along with the progress of business activities and development of interactive learning, projectors have gradually become indispensable image display apparatuses in many kinds of business events and the image display technology has been advancing from the liquid crystal display to the digital light processing (DLP).
The digital light processing technology employs the reflected light, which is modulated by a spatial light modulator (SLM), such as a commonly-known digital micromirror device (DMD) that has an array of micromirrors. By controlling the tilt angle of each micromirror individually, every micromirror can be selectively arranged in two states, such as an “on” state and an “off” state. Referring to FIG. 1, a block diagram of a conventional image display apparatus is illustrated. When the light beam provided by the light source 10 travels through the integrator 20 and the filter 30 and impinges on the DMD 40, the controller 70 determines, according to image signals, the corresponding state of each micromirror. When an image signal is on, the corresponding micromirror is disposed in the on state, and the light beam is reflected to form an image on a screen 50. When the image signal is off, the corresponding micromirror is disposed in the off state, and the light beam is reflected to other direction and absorbed by the absorber 60 or converted to heat.
Brightness, resolution, weight, and lifetime of the light source are indices for determining the quality of a projector. The brightness, which indicates the intensity of light projected on a screen, especially determines whether a projector can have an effective image in a bright environment. If the brightness achieves some level, the projector can have a projected image in good quality without the need of darkening the environment or turning off the facility's light.
The light source is a component directly relating to the brightness of a projector. In general, a projector displays an image of higher brightness as the light source has greater power (or wattage). However, purely increasing the power of the light source to improve the brightness cannot improve the overall quality of a projector because, for example, a light source of greater power generates more heat, which requires a better heat dissipation mechanism, such as a larger fan. When the fan becomes larger, the noise becomes louder, and the size of the projector increases at the same time. Therefore, increasing the power of the light source to improve the image brightness must sacrifice some quality in other aspects.
Therefore, there is a need to provide an image display apparatus for improving the image brightness without inducing more problems, such as heat.